A Laboratory Investigation into the Effect of Water Content on the CBR of a Subgrade soil

Summary

Residual soils, most of which are lateritic serve as subgrade and even sub-base and base layers for road and highway pavements in the subregion. However, the material is known to undergo substantial strength reduction when they become saturated with water. An understanding of the dependence of the CBR strength of local soils on water content will contribute towards better design and maintenance practices. Samples of soil from a study site were prepared by laboratory compaction at the optimum water content using different levels of compaction to obtain samples at different densities. The remoulded samples were then subjected to different levels of wetting in a water tank and different degrees of drying in the laboratory and the CBR determined. The variation of the CBR with the water content is presented and discussed and related to the matric suction.